1. Field of the Invention
This invention relates to a composition for percutaneous drug adminstration which is capable of promoting percutaneous drug absorption and a method of promoting percutaneous drug absorption.
2. Description of the Prior Art
Hithertofore the purpose of the application of a drug composition to the skin has been to produce some or other local effect on the skin or subcutaneous tissues, disinfectant, analgesic, itch-killing or antiinflammatory effect. For the purpose of producing a systemic effect, oral administration of tablets or injection has been made use of so far. Tablets for oral administration are, however, have drawbacks: active ingredients are liable to primary metabolism in the liver after their absorption, or they are absorbed only to an insufficient extent, or, when a lasting effect is desired, an unnecessarily high concentration in the body is reached, although temporarily. Oral administration of indomethacin, for instance, produces on gastrointestinal disorders. Administration by injection, on the other hand, can result in rapid absorption but requires skilled persons such as physicians.
In recent years it has been proposed to administer drugs percutaneously for the purpose of producing a systemic effect to thereby alleviate or overcome the above-mentioned adverse effects or drawbacks.
Percutaneous administration of drugs is advantageous, for example, in that the effects of the drugs can be easily maintained, that the drug concentration in the body can be controlled, or that the drugs scarcely undergo primary metabolism in the liver because they enter the blood circulation through cutaneous tissues.
However, the skin, when normal, essentially has the so-called barrier function to prevent invasion of foreign substances into the body. Therefore the administration of drugs via the skin has been limited to local uses. For the purpose of producing a systemic effect, an auxiliary agent for promoting percutaneous absorption is required and recent proposals include various substances. Thus, for example, U.S. Pat. No. 3,551,554 discloses dimethyl sulfoxide, and also dimethylacetamide, dimethylformamide, methyl decyl sulfoxide, and so forth.
Also known are absorption-promoting agents in combination with lower alkylamide, for exmaple, combinations of dimethylacetamide and ethyl alcohol, isopropyl alcohol or isopropyl palmitate (U.S. Pat. No. 3,472,931) or combinations of 2-pyrrolidone and an appropriate oil or an ester between an straight-chain fatty acid and an alcohol (U.S. Pat. No. 4,017,641). However, they are not yet fully satisfactory as absorption-promoting agents with respect to their effect, safety and feel upon use.